Electromechanical drive mechanism



A ril 7, 1964 A. s. HOPPING 3,127,782

ELECTROMECHANICAL DRIVE MECHANISM Filed April 6. 1960 mam? T e. 711M113- If! VOLT MAINS 75 80 v 7 ax T I INVENTOR. HLVl/V SHOPP/NG ATTORNEY United States Patent 3,127,782 ELECTRDMECHANECAL DRIVE MECHANISM Alvin S. Hopping, Nolans Point, Lake Hopatcong, NJ. Filed Apr. 6, 196a, Ser. No. 20,375 6 Claims. (Cl. 74-405) The present invention relates to electromechanical devices. More particularly it relates to a mechanically assisted travelling solenoid.

Electromagnetic devices in which a magnetic field created by the passage of current through a field coil is employed to move directly a plunger or travelling member are well known to the art. In such devices the throw or distance which the travelling member moves and the force which it transmits are entirely direct functions of the strength of the magnetic field created by the passage of current through the field coil.

The present invention has as one of its objects an electromagnetic device of increased sensitivity in which the distance of travel (or stroke) and the force transmitted (or lift) by a plunger or travelling member are very substantially greater than that available from the energy of the magnetic field created by the passage of current through its field coil.

A further object of the present invention is an electromagnetic device having a travelling plunger in which plunger travel is mechanically assisted by a driving means engaged automatically only on energization of the field coil, and disengaged on de-energization of the field coil.

Yet another object of the invention is an electromechanically aided travelling solenoid system in which a plurality of solenoids are mechanically aided by a common source of power.

Other objects of the invention include, inter alia, the provision of a compact, simply constructed electromagnetic device utilizing a field coil of small physical size and minimum wire diameter and in which travel of the plunger is mechanically assisted by an auxiliary plunger driving means which is positively engaged during a portion of the plunger travel, and is disengaged entirely at other times.

In accordance with the present invention an electromagnetic device comprises a movable member, driving means for mechanically engaging and driving said movable member away from a normal rest position, biasing means for normally disengaging said movable member and said driving means and retaining said movable member in said normal rest position, and an electromagnetic field coil adapted, on passage of an electric current therethrough, to develop a magnetic engaging force which counteracts and overcomes said normal disengaging bias etween said movable member and said driving means.

The invention will be further described in connection with the accompanying drawings which are to be considered as exemplary of the invention and do not constitute limitations thereof.

In the drawings:

FIG. 1 illustrates, in sectional elevation along the line 1-1 of FIG. 2 in the direction indicated, the construction of a mechanically assisted solenoid in accordance with the present invention,

FIG. 2 is a view in sectional elevation along the line 22 of FIG. 1 in the direction indicated illustrating a device in which a plurality of travelling members are ariven by a common source of mechanical assistance, and also includes a schematic diagram of an electrical wiring system suitable for use therewith, and

FIG. 3 is a detail sectional view in elevation of that portion of FIG. 1 indicated by arrows 3-3.

In FIGS. 13 a travelling assembly indicated generally by the character Ml, comprises a field coil 12, 12 of 3,l2?,782 Patented Apr. 7, 1964 copper wire wound about a core 14. The leads 16, 18 to the coil 12, 12' terminate at tie points 210 and 22.

The core 14 is supported between the sides of a box frame 24 open at its ends 26 and 28. The frame 24 is fabricated, from a magnetic material of high permeabil- 1ty.

The bottom side 30 of the frame is provided throughout its length with a narrow flux-gap 32, which extends through the side of the frame and also throughout the length of the members of a rack 34 which is carried on and depends from the outside of the bottom 3% of the frame 24. Similarly to the frame, the rack is fabricated of ferromagnetic material of high permeability.

Projecting from one end 26 (hereinafter referred to as the leading end) of the frame 24 is a plunger 36 of rectangular cross-section. The plunger extends through an opening or passageway 33 in one vertical Wall 40 of a rigid, supporting bed 42. The passageway 38 is rectangular in shape, being only slightly wider than the width of the plunger 36, but being substantially higher than the height thereof so as to permit considerable vertical displacement of the plunger 36 and frame 24 without extensive lateral motion thereof.

A biasing spring 44 is affixed at one end to the top of the frame 24 and is affixed at its other end to an eye 46 extending from a rear vertical wall 48 of the supporting bed 42.

Also mounted on the supporting bed 42 is a drive motor 56 adapted to rotate a shaft 52 carrying a toothed drive gear 54 fabricated of a magnetic material. The idle end 56 of the shaft 52 is journaled in a bearing 58 in a third vertical wall es of the support bed 42.

The rack 34 carries teeth 62 which are dimensioned to engage positively the teeth 64 of the drive gear 54.

As illustrated in FIG. 2, a plurality of travelling assemblies 10 may be provided in conjunction with separate (or, if desired, a unitary) drive gears 54 carried in common by the motor driven shaft 52.

The tie points 20 and 22 are connected through conduits 68 and 7t) (and optionally through a switch 72) in parallel with conduits '74 and 76 supplying power to the drive motor Ell, to conduits 73 and 80 leading through switch 32 to volt mains.

In operation, closing of the switch 82 energizes the motor 59 causing rotation of the drive gear 54 in the direction indicated in FIG. 1. On passage of current through the field coil, i.e., on closing of switch 82 and optional switch 72, a magnetic circuit is established through the frame 24 of the travelling assembly 10 and across the flux-gap 32 in the bottom 30 thereof and rack 34. Magnetic attraction between the travelling assembly 10 and the rotating drive gear 54 overcomes the restraining action of the biasing spring 44 and causes the teeth 62 of the rack to mesh with the teeth 64 of the drive gear 54. As a result of the fact that the teeth 62 of the rack are proportioned to engage positively those of the gear 54-, the entire travelling assembly 10 is driven laterally toward the vertical wall 40 of the supporting bed 42, impelling the plunger 36 through the passageway 38. Lateral, positive drive of the travelling assembly continues until the leading end 26 of the frame 24 approaches the magnet-attracting vertical wall 40 of the support bed 42. When the leading end 26 of frame 24 approaches the proximity of the magnet-attracting wall 40, mechanical inertia and the magnetic attraction between the travelling assembly 10 and the wall 40 cause the assembly 10 to seat against the wall 40, after which the assembly 10 is held to the wall 40 magnetically. In this position the last tooth of the rack 34 is disengaged from and clears the teeth of the rotating gear 54.

The solenoid may be de-energized by stopping the flow of current through an individual field coil, e.g., as by opening switch 72. When current flow through the field coil ceases, the travelling assembly is no longer held to or attracted by either the vertical wall 40 or the drive gear 54. As a result, the biasing spring 44 urges the travelling assembly 10 away from the vertical side wall 40 and upwards, over and out of contact with the teeth of the drive gear 54, thereby returning the assembly in an arcuate path to its initial or rest position.

The upward displacement of the travelling assembly to clear the drive gear is occasioned by the fact that the spring 44 is afiixed to the rear vertical sidewall 48 of the supporting bed 42 at a position substantially above the location at which its other end is affixed to the frame 24. Of course, the vertical enlargement of the bearing opening or passageway 38 in the bed wall 40 is also of importance in that it permits the necessary vertical play of the plunger 36 associated with the vertical displacement of the entire travelling assembly.

As an alternative to opening the switch 72 in the current supply to the field coil 12, the supply of current to both the coil and any coils in parallel therewith and also to the drive motor 50 may be eliminated by opening the switch 82.

It will now be appreciated that the present invention makes available to the art a travelling solenoid characterized by a plunger stroke and lift of virtually unlimited magnitude, and that in comparison to the travelling solenoids of the prior art, the present mechanically assisted electromagnetic device is of vastly increased sensitivity inasmuch as the plunger stroke and lift are substantially independent of the current supplied to the field coil.

It Will also be apparent that the instant mechanically assisted electromagnetic device may be constructed with a single source of assistance ganged to a plurality of travelling members, e.g. 10, 10' thus facilitating economical operation in a device wherein a large number of travelling members may be employed, as in musical instruments, electric typewriters, switching systems, sequential valve operations, mechanical movements, and the like.

It is to be understood that the invention herein illustrated and described is to be limited only by the scope of the appended claims and that various changes may be made in details of construction without departing from the true spirit of the invention.

What is claimed is:

1. A mechanically assisted electromagnetic device comprising a ferromagnetic pinion gear; means for driving said pinion gear in rotary motion; and a travelling assembly which includes a plunger, a rack linked to said plunger by linking means and adapted to engage said pinion gear, a resilient member for normally disengaging said rack and pinion gear and retaining said travelling assembly in a normal rest position, an electromagnetic field coil adapted, on passage of electric current therethrough, to develop a magnetic engaging force between said rack and said ferromagnetic pinion gear sufficient to overcome the disengaging force exerted by said resilient member and cause said rack and pinion gear to engage; whereby such engagement of said rack and pinion gear while said pinion gear is driven in rotation impels said travelling assembly from its normal rest position to an actuated position, and a ferromagnetic stop disposed to engage said linking means when said assembly is so impelled to said actuated position.

2. A mechanically assisted electromagnetic device as set forth in claim 1 wherein a plurality of travelling assemblies are each driven by a magnetic pinion gear rotatably driven by a single driving means,

3. A mechanically assisted electromagnetic device as set forth in claim 1 wherein said pinion gear driving means comprises an electric motor wired in electrical parallel with said field coil.

4. A mechanically assisted electromagnetic device comprising a frame; a plunger, an electromagnetic field coil and a ferromagnetic rack each carried on said frame; a pinion gear adapted to engage said rack and drive said frame and said plunger carried thereon; electric means for rotating said pinion gear; a spring normally disengaging said rack and said pinion gear and retaining said plunger in a normal rest position; said pinion gear being ferromagnetic; whereby on passage of electric current through said field coil and pinion gear rotating means there is established a magnetic attractive force between said rack and said ferromagnetic pinion gear which overcomes the disengaging force of said spring and causes said rotatably driven pinion gear to engage said rack and impel said frame and plunger carried thereon from a normal rest position to an actuated position, and a ferromagnetic stop disposed to engage said frame when said frame is so impelled to said actuated position.

5. A mechanically assisted electromagnetic device comprising a cylindrical field coil, a rectangular magnetic frame encircling said field coil, said frame being open on one end thereof and carrying a toothed rack, said frame and said rack having a common flux gap therein, a plunger mounted on said frame and projecting from said open end thereof, a ferromagnetic pinion gear adapted to engage and drive said rack, means for driving said pinion gear in rotation, biasing means for normally disengaging said rack and ferromagnetic pinion gear and retaining said plunger in a normal rest posiiton, said field coil being adapted, on passage of electric current therethrough, to establish magnetic flux across said gap and thereby develop a magnetic attraction between said rack and said driven pinion gear, whereby said pinion drives said plunger-carrying frame a displacement distance equal to the length of said rack, and a ferromagnetic stop disposed to engage said open end of said frame when said frame is so displaced.

6. A mechanically assisted electromagnetic device comprising a ferromagnetic pinion gear, a travelling assembly which includes a plunger and a rack lined to said plunger by linking means and adapted to engage said pinion gear, biasing means for normally disengaging said rack and pinion gear and retaining said travelling assembly in a normal rest position, an electromagnetic field coil adapted, on passage of electric current therethrough, to develop a magnetic engaging force between said rack and said ferromagnetic pinion gear sufiicient to overcome said bias and cause said rack and pinion gear to engage; whereby such engagement of said rack and pinion gear while said pinion gear is driven in rotation impels said travelling assembly from its normal rest position to an actuated position, and a ferromagnetic stop disposed to engage said linking means when said assembly is so impelled to said actuated position.

References Cited in the file of this patent UNITED STATES PATENTS 1,243,169 Herman Oct. 16, 1917 2,525,443 Bischoff Oct. 10, 1950 2,893,257 Schulte July 7, 1959 2,921,479 Thomas Ian. 19, 1960 FOREIGN PATENTS 851,884 Germany Fur-s Oct. 9, 19,52 

1. A MECHANICALLY ASSISTED ELECTROMAGNETIC DEVICE COMPRISING A FERROMAGNETIC PINION GEAR; MEANS FOR DRIVING SAID PINION GEAR IN ROTARY MOTION; AND A TRAVELLING ASSEMBLY WHICH INCLUDES A PLUNGER, A RACK LINKED TO SAID PLUNGER BY LINKING MEANS AND ADAPTED TO ENGAGE SAID PINION GEAR, A RESILIENT MEMBER FOR NORMALLY DISENGAGING SAID RACK AND PINION GEAR AND RETAINING SAID TRAVELLING ASSEMBLY IN A NORMAL REST POSITION, AN ELECTROMAGNETIC FIELD COIL ADAPTED, ON PASSAGE OF ELECTRIC CURRENT THERETHROUGH, TO DEVELOP A MAGNETIC ENGAGING FORCE BETWEEN SAID RACK AND SAID FERROMAGNETIC PINION GEAR SUFFICIENT TO OVERCOME THE DISENGAGING FORCE EXERTED BY SAID RESILIENT MEMBER AND CAUSE SAID RACK AND PINION GEAR TO ENGAGE; WHEREBY SUCH ENGAGEMENT OF SAID RACK AND PINION GEAR WHILE SAID PINION GEAR IS DRIVEN IN ROTATION IMPELS SAID TRAVELLING ASSEMBLY FROM ITS NORMAL REST POSITION TO AN ACTUATED POSITION, AND A FERROMAGNETIC STOP DISPOSED TO ENGAGE SAID LINKING MEANS WHEN SAID ASSEMBLY IS SO IMPELLED TO SAID ACTUATED POSITION. 